I can't delete files. The trash icon doesn't appear in the top right corner of the screen.

Hi ​@MTYJJK, 

Welcome to Box Community, and we’ll assist with your content deletion. 

It shows that the folders in your Box account are all collaborated folders. And as a collaborator, your ability to delete contents can be limited depending on the permission you have in the folder. 

To know more, please see this article. In the meantime, If there are files that you need to delete, kindly reach out to the folder owner. 

Hope it helps, and please feel free to reply if you have additional questions.